Clinical features in enteritis due to Vibrio parahemolyticus

Inflammation and disintegration of intestinal villi in an experimental model for Vibrio parahaemolyticus-induced diarrhea

Vibrio parahaemolyticus is a leading cause of seafood-borne gastroenteritis in many parts of the world, but there is limited knowledge of the pathogenesis of V. parahaemolyticus-induced diarrhea. The absence of an oral infection-based small animal model to study V. parahaemolyticus intestinal colonization and disease has constrained analyses of the course of infection and the factors that mediate it. Here, we demonstrate that infant rabbits oro-gastrically inoculated with V. parahaemolyticus develop severe diarrhea and enteritis, the main clinical and pathologic manifestations of disease in infected individuals. The pathogen principally colonizes the distal small intestine, and this colonization is dependent upon type III secretion system 2. The distal small intestine is also the major site of V. parahaemolyticus-induced tissue damage, reduced epithelial barrier function, and inflammation, suggesting that disease in this region of the gastrointestinal tract accounts for most of the diarrhea that accompanies V. parahaemolyticus infection. Infection appears to proceed through a characteristic sequence of steps that includes remarkable elongation of microvilli and the formation of V. parahaemolyticus-filled cavities within the epithelial surface, and culminates in villus disruption. Both depletion of epithelial cell cytoplasm and epithelial cell extrusion contribute to formation of the cavities in the epithelial surface. V. parahaemolyticus also induces proliferation of epithelial cells and recruitment of inflammatory cells, both of which occur before wide-spread damage to the epithelium is evident. Collectively, our findings suggest that V. parahaemolyticus damages the host intestine and elicits disease via previously undescribed processes and mechanisms.

The marine bacterium Vibrio parahaemolyticus is a leading cause worldwide of gastroenteritis linked to the consumption of contaminated seafood. Despite the prevalence of V. parahaemolyticus-induced gastroenteritis, there is limited understanding of how this pathogen causes disease in the intestine. In part, the paucity of knowledge results from the absence of an oral infection-based animal model of the human disease. We developed a simple oral infection-based infant rabbit model of V. parahaemolyticus-induced intestinal pathology and diarrhea. This experimental model enabled us to define several previously unknown but key features of the pathology elicited by this organism. We found that V. parahaemolyticus chiefly colonizes the distal small intestine and that the organism's second type III secretion system is essential for colonization. The epithelial surface of the distal small intestine is also the major site of V. parahaemolyticus-induced damage, which arises via a characteristic sequence of events culminating in the formation of V. parahaemolyticus-filled cavities in the epithelial surface. This experimental model will transform future studies aimed at deciphering the bacterial and host factors/processes that contribute to disease, as well as enable testing of new therapeutics to prevent and/or combat infection.

Cholera and other types of vibriosis: a story of human pandemics and oysters on the half shell

Vibrios are ubiquitous in the aquatic environment and are commonly present in or on shellfish and other seafood. A small subset of strains/species are able to cause human disease, including the cholera toxin-producing strains of Vibrio cholerae that are responsible for epidemic/pandemic cholera; thermostable direct hemolysin-producing strains of Vibrio parahaemolyticus; and Vibrio vulnificus, which can cause fulminant sepsis. Cholera outbreaks can be initiated by transmission of "epidemic" V. cholerae strains from their environmental reservoir to humans through seafood or other environmentally related food or water sources. "Nonepidemic" strains of V. cholerae and strains of other Vibrio species, including V. parahaemolyticus and V. vulnificus, are generally acquired by eating seafood (particularly raw oysters/oysters on the half shell). Although the primary clinical manifestation of infection with these strains is gastroenteritis, they can also cause wound infections and (particularly for V. vulnificus) septicemia in persons who have liver disease or are immunocompromised.

Gastroenteritis and antibiotic-associated diarrhea

Acute gastroenteritis is a common cause of emergency and office visits. This article reviews causes, pathogenesis, diagnosis, prevention, and treatment. The incidence of antibiotic-associated colitis is increasing worldwide as a consequence of widespread use of broad-spectrum antibiotics for various illnesses. The pathogenic organism, Clostridium difficile, produces two enterotoxins, toxin A and toxin B, that cause colonic mucosal inflammation. C. difficile infection presents with a wide range of clinical manifestations, from asymptomatic carriers to life-threatening pseudomembranous colitis.

Infectious colitis excluding E. coli O157:H7 and C. difficile

Colitic infection caused by a variety of organisms may have an extremely varied presentation, course, and treatment response. Current data have provided great insights into the pathophysiology of these various organisms and their clinical presentation, course, and treatment outcomes. As clinicians develop a better understanding of the colon, its immunologic defense mechanisms, and the virulence factors of such organisms, they will be better able to evaluate these infections as well as newer colonic infections yet unknown. It is important to know if and when to treat such organisms to prevent the dilemma of drug-resistant strains, as seen already in a variety of well-known infections, such as Campylobacter and others. Knowledge of such colonic targets will be more important in an era of ever-growing resistance to and wide use of antibiotic regimens.

Adherence targets of Vibrio parahaemolyticus in human small intestines

Formalin-fixed human small intestinal mucosa with mucus coating, villi, and lymphoid follicle epithelium at the mucosal surface was used to test the adherence sites of clinically isolated (Kanagawa phenomenon-positive) strains of Vibrio parahaemolyticus. V. parahaemolyticus strains grown on CFA agar (supplemented with 3% NaCl) for ca. 3 h at 37 degrees C possessed various levels of cell-associated hemagglutinins (HAs) which were detected with human or guinea pig erythrocytes. The observed adherence abilities of V. parahaemolyticus strains to human small intestinal mucosa correlated roughly with the HA levels of the strains. Under the test conditions, ileal lymphoid follicle epithelium (especially M cells) provided the best adherence target for V. parahaemolyticus. Adherence to villus absorptive cells or to mucus coating was observed at lower levels. In addition, all 3-h-grown V. parahaemolyticus strains tested produced high levels of HAs as detected with rabbit erythrocytes. The strains were all strikingly motile. In contrast, V. parahaemolyticus strains grown on CFA agar (supplemented with 3% NaCl) for ca. 20 h at 37 degrees C had much lower levels of HAs, adherence abilities, and motility. In contrast to the above observations, piliation of V. parahaemolyticus was more extensive at ca. 20 h of incubation at 37 degrees C than at ca. 3 h of incubation at 37 degrees C. The remarkable ability of V. parahaemolyticus to adhere to lymphoid follicle epithelium was also confirmed by using rabbit small intestinal mucosa.

Vibrio parahaemolyticus gastroenteritis. An outbreak associated with raw oysters in the Pacific northwest

During a 3-month period in the late summer and fall of 1981, six cases of gastroenteritis and one wound infection due to Vibrio parahaemolyticus were reported to public health agencies in Washington and Oregon. An investigation revealed that all of the gastroenteric illnesses were associated with eating raw oysters; that oysters eaten by five of the six patients were harvested at four divergent sites at Willapa Bay, Washington, a large commercial growing area; and that the V. parahaemolyticus isolates from those five patients were all Kanagawa positive, belonged to serotype 04:K12, and exhibited an atypical biochemical reaction, urea hydrolysis. No further cases linked to Willapa Bay oysters have been reported, and the infecting strain could not be found in sediment samples from the bay in February 1982. Thus, even though the origin of this self-limiting outbreak is obscure, the investigation demonstrated that the geographic distribution of V. parahaemolyticus infection in the United States includes the Pacific seacoast . Furthermore, oysters must be considered, along with crabs, shrimp, and lobster, as a vehicle of transmission of this infection in the United States.

Vibrio parahaemolyticus and related halophilic Vibrios

Approximately 30 years have elapsed since Dr. Fujino's original discovery that Vibrio parahaemolyticus (then termed Pasteurella parahemolytica) was the cause of "summer diarrhea" in Japan. Since that finding, V. parahaemolyticus has been established as a cause of gastroenteritis in numbers and places approaching global proportions. It has been isolated in marine and estuarine areas almost worldwide and despite its halophilic nature, V. parahaemolyticus has been isolated from saline-free waters. The relationship of this organism to the environment reveals a close association with other marine organisms especially copepods on which the Vibrios depend for survival in winter months and growth in summer months. There is a uniquely provocative disparity between human strains of V. parahaemolyticus which are Kanagawa phenomenon (KP) positive and the environmental strains which to a large extent are KP negative, the significance being that pathogenicity is measured according to the Kanagawa phenomenon (hemolytic activity) reaction. The hemolysin of the pathogenic strains is a thermostable, cardiotoxic protein, which thus far has not been implicated in the mechanism(s) which causes human gastroenteritis. The interest in this organism has been widened in recent years by the finding that similar organisms, V. alginolyticus, lactose positive vibrios and group F vibrios also cause serious disease in humans.

Fulminating lactose-positive Vibrio septicemia

Recently cases of tissue invasion by as yet unnamed marine vibrios which were morphologically and biochemically similar to both Vibrio parahemolyticus and V. alginolyticus, but not identical with either of them, have been described. We have seen a patient who had serious widespread tissue infection with a halophilic, Gram-negative bacterium which was isolated from blood and leg lesions. The organism had the characteristics of the genus Vibrio, and lactose fermentation and ONPG reactions were positive. It also had a lower tolerance for sodium chloride in the nutrient broth compared with the above two vibrios. The isolate seems identical to the lactose positive (L+) Vibrio described by HOLLIS et al. (1976). Tissue infection resulting in severe necrotizing cellulitis and vasculitis was demonstrated at autopsy.

Campylobacteriosis in man: pathogenic mechanisms and review of 91 bloodstream infections

Five patients with Campylobacter fetus(previously called "Vibrio fetus") bacteremia are presented with enteric symptoms in four patients, a self-limited course in three, and with possible nosocomial infection in one patient who had disseminated malignancy. The clinical syndromes of 91 bacteremic patients with campylobacteriosis and C. fetus taxonomy and pathogenicity are reviewed. Studies of potential pathogenic mechanisms in enteric infections failed to reveal the production of either heat-stable or heat-labile, cholera-like enterotoxin, cytotoxicity or invasiveness. In comparison with different species of vibrio infections, C. fetus appears to produce disease by a different mechanism, one which involves a bloodstream infection, perhaps following penetration through the intestinal mucosa as has been demonstrated experimentally with salmonellae and yersinia. Such a pattern is consistent with the clinical pattern of C. fetus infections and the experimental studies reported herein.

Superoxide dismutase and catalase levels in halophilic vibrios

Superoxide dismutase (SOD) and catalase (CAT) levels were determined for several aerobically grown halophilic vibrios and compared with those found in aerobically grown Escherichia coli K-12. The SOD levels ranged from 25 to 103.6 U/mg of protein for the vibrios compared with 44.6 U/mg of protein for E. coli. The CAT levels ranged from 2.1 to 32.1 U/mg of protein. Electrophoretic analysis of cell extracts revealed that the halophilic vibrios tested possessed only one detectable SOD enzyme, except one strain which possessed two distinct enzymes, as compared with the three SOD enzymes in aerobically grown E. coli K-12. A comparison of anaerobically and aerobically grown vibrios revealed a three- to fourfold increase in SOD activity in the aerobic cells, suggesting that oxygen acts as an inducer for SOD in the vibrios as has been reported for E. coli. In one strain, Vibrio parahaemolyticus 27519, both SOD enzymes were observed in low levels in anaerobic and at higher levels in aerobically grown cells as compared with only one SOD enzyme in anaerobically grown E. coli. This suggests that differences in SOD regulation occur between the two genera. Our results indicate that halophilic vibrios possess SOD, which could enhance viruulence by allowing the organisms to survive in oxygenated environments.

Vibrio alginolyticus infections in Hawaii

Clinical and bacteriological features of eight cases of Vibrio alginolyticus infections in Hawaii are presented. These isolates occurred in superficial sites, primarily related to infections caused by swimming.